HVAC Issue

[edfiero]

I am experiencing a issue with the heat in my 08 GT. Funny thing is that I never noticed in the previous 2 years of owning the car. I've always run the HVAC in single zone mode at 68 or 69 degrees with AUTO mode off during the winter. Lately I've been feeling cold when it is set to 68, I've found I need to turn it up to 74 or even 76 to stay warm even though its not that cold outside. What I discovered was that although nice hot air is blowing from the floor vent, there is a small, but noticable amount of COLD air blowing out of the windshield vent.I have the following HVAC config

68 degrees
AUTO mode OFF
AC mode OFF
Recirculation OFF
Single Zone
Air from Floor vent Only.
Blower Speed - Doesn't matter problem is noticable from a setting of 1 to 10 or more.

Any ideas how to correct this? When I select the floor only air mode, I would not expect any air to come out at the windshield, and even if there was an issue with the air control doors, which I don't think there is, I would expect to get hot air up there, not cold. And to repeat, when the cold air is coming out at the windshield, the air at the floor vents is still warm.

I'm not sure it happens all the time. I only see it occassionally or after I've been driving a while. I'd hate to take it to the dealer and have them keep the car a week trying to recreate the problem, or tell me they don't see an issue. I'd just prefer to fix it myself. Any ideas?

[TLS]

Forgot to add in the other forum....

I noticed over the past year or so that when the ENTIRE system is OFF (how I like to run when temp outside is "room temp" and I don't need it hotter or colder or the A/C compressor cycling), I get outside air coming through vents at speed. I don't think you can totally stop ALL air from coming through.

Not sure if this helps or not, just thought I'd add it here.

And I guess you do know from my other forum post that the sunlight sensor affects things in weird ways (mostly good). Test it by putting something over the sensor when this condition occurs and see if it changes temps.


My total guess is that the HVAC is attempting to keep your windshield de-fogged the best it can with you having A/C set to off.

[G8GTKID]

When you have it on the floor only mode with the circulation off, the blower will only blow the air through the floor wents of course, but with the circulation off the outside vent is still open to all other vents inside the car. Thats where your getting your cold air is from the air outside slidding through the outside vent as you move. Try sitting still with the same set-up and see if you can still feel cold air coming through. If not thats what the issue is, and nothing is wrong with your HVAC its pretty typical. :thumbsup:

[G8GTKID]

Forgot to add in the other forum....

I noticed over the past year or so that when the ENTIRE system is OFF (how I like to run when temp outside is "room temp" and I don't need it hotter or colder or the A/C compressor cycling), I get outside air coming through vents at speed. I don't think you can totally stop ALL air from coming through.

Not sure if this helps or not, just thought I'd add it here.

And I guess you do know from my other forum post that the sunlight sensor affects things in weird ways (mostly good). Test it by putting something over the sensor when this condition occurs and see if it changes temps.


My total guess is that the HVAC is attempting to keep your windshield de-fogged the best it can with you having A/C set to off.

Your is kind of the same deal. Im like you and when its nice outside I like to just shut the HVAC off and crack the windows, but there is still air that escapes through the outside vent. When you shut off the HVAC hit the circulation button and it will close the outside vent and that will not allow any air to come through the inside vents.